Added option to use a specified image for menu cursor instead of drawing a triangle.
Battlesystem - changed how monster stats are shown, made start-battle message default to blank, made meta-menu title customizable. Created fixedDisplayBoxes feature in menu system to support any number of arbitrary fixed display boxes that are not part of the menu stack.
Issue #59 - factored all hard-coded screen size references out of rpgbase; they must now be specified in userland code. Specifying an html base element for the menus (or not) now determines whether css menus or canvas menus will be used.